In a conventional Multimedia Over Coaxial Alliance (MoCA) network, data packets are transmitted over a coaxial communication channel. Communication through the network is managed by a Network Coordinator node (NC) that transmits Beacons and Media Access Plan (MAP) packets. The Beacons are transmitted at regular intervals (e.g., every 10 ms) and identify the channel time clock (CTC), the MoCA network version, the time of the next admission control frame (ACF), and when a NC handoff will occur (e.g., when the NC changes from one node to another node).
MAP packets are transmitted more frequently by the NC than are Beacons and provide scheduling information that identify when each network node will be transmitting data through the network. Each node connected to the network relies on the MAPs in order to transmit and receive data through the network. Many factors may prevent a network node from correctly receiving a MAP. For example, GSM interference caused by a cellular phone operating near a network node may corrupt a MAP by creating co-channel and/or adjacent channel interference with the network node. Due to the length of GSM interference, e.g., approximately 0.577 ms, a network node may miss or incorrectly process one or more MAPs.
In conventional MoCA networks, losing a MAP packet will prevent a network node from receiving the subsequently transmitted MAPs as each MAP identifies a MAP packet transmission interval, e.g., the interval when the next MAP will be transmitted. FIG. 1 is a timing diagram illustrating a network node failing to receive a MAP and then recovering from this failure in a conventional MoCA network. As illustrated in FIG. 1, NODE1 fails to receive MAP2 from the NC. The NC continues to broadcast MAPs over the network; but NODE1 fails to receive or correctly process MAP3 thru MAP6 because NODE1 failed to receive or correctly process MAP2. In a conventional MoCA network, NODE1 must wait until it receives and processes the next Beacon, BEACON2, to determine the MAP transmission interval and once again receive and correctly process MAP packets, e.g., MAP7. Since MAPs are more frequently transmitted than the Beacons, a node that fails to receive or correctly process one MAP packet may not receive the next several MAPs as it will have to wait for the next Beacon. Thus, once a node fails to receive a MAP, the node is essentially disconnected from the network for a period (from MAP2 to MAP7 for the example of FIG. 1) as it will not receive subsequent MAP packets and determine when data is going to be transmitted through the network until the node receives the next Beacon. In addition, the node will not be able to request any time slots from the NC for transmitting any buffered data packets until the next Beacon is received.
Accordingly, an improved method for recovering from missing a MAP transmission is desirable.